Using Nuclear Magnetic Resonance to Troubleshoot a Stability Issue in a Real-World Formulation Chassis-Application to...

Area of Science:

• Analytical Chemistry
• Materials Science
• Consumer Healthcare Product Development

Background:

• Consumer healthcare product formulations can degrade over time, affecting stability and efficacy.
• Packaging plays a critical role in maintaining the integrity of pharmaceutical and cosmetic products.
• Discoloration in oral cleansers containing salicylic acid and hydrogen peroxide was observed, necessitating an investigation into its causes.

Purpose of the Study:

• To investigate the origins of discoloration in proprietary experimental formulations (PEFs) of oral cleansers.
• To identify the chemical species responsible for discoloration and understand their formation mechanisms.
• To evaluate the interaction between the formulation and its packaging materials.

Main Methods:

• Utilized Nuclear Magnetic Resonance (NMR) spectroscopy, including 1D/2D NMR and diffusion-ordered NMR spectroscopy (DOSY), for rapid analysis of complex mixtures.
• Employed Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Attenuated Total Reflectance Infrared Spectroscopy (ATR-IR) to study formulation-container interactions.
• Assessed the formation of degradants as a function of temperature and pH to elucidate degradation pathways.

Main Results:

• Identified catechol as the primary source of discoloration, forming at ppm levels over several weeks.
• Confirmed the role of both spontaneous formulation degradation and interaction with packaging materials in the discoloration process.
• Tentatively assigned the root cause of discoloration to a surface titanium complex involving salicylic acid and other hydroxy carboxylic acids.

Conclusions:

• NMR is invaluable for analyzing complex proprietary mixtures in consumer-centric applications, outperforming conventional techniques.
• Understanding degradation pathways supports toxicology assessment, ensuring consumer safety and aiding manufacturers.
• This research provides insights into material selection for consumer healthcare products, considering stability, safety, and recyclability.